Name: Jesse Colangelo-Lillis

Email: jrcl@u.washington.edu

Author: Jesse Colangelo-Lillis1* and Jody Deming1

Author affiliation: 1School of Oceanography/Astrobiology Program, University of Washington, Seattle, WA, USA * Presenting author

Abstract title: Implications of viral lysogeny and functional transduction in sea ice microbes

Absstract:

Frozen environments on this planet date to the start of the Proterozoic eon, with intermittent glacial periods occurring thereafter. Microbes adapted to grow at subzero temperatures have either evolved on Earth multiple times or else found unfrozen refugia sufficiently cool to escape extinction. Sea ice supports a predominance of prokaryotes adapted to cold activity, and so makes an obvious target for the study of evolution. Modeling results indicate virus-bacteria contact rates in sea ice brines are amongst the highest described. Post-infection lysogeny occurs with greater frequency both under stressful replication conditions, and in the Arctic (compared to other oceans). Whole genome sequences of cold-adapted bacteria, including from sea ice, suggest incorporation of viral genomes and introduction of numerous genes via nonlethal viral transduction. In conditions adverse to host cell growth, prophages that impart metabolic advantages to their hosts should persist over evolutionary time scales. The abundance of viruses and their ability to both accrue and disseminate foreign genetic material may have contributed, and may still contribute, to rates of bacterial adaptation more rapid than achievable by vertical gene transfer. Recent work in our laboratory has shown that viruses can be infective at low temperature (?12?C) and high salt concentration (16%), mimicking conditions in the brine inclusions of Arctic winter sea ice. Via laboratory, genomic and field work, we aim to establish a phage-host system that facilitates study of evolution, rates of infection, incidence of lysogeny and incorporation of functional genes into host genomes under extreme thermal and saline conditions with high virus-host contact rates.